Smoothing Calculator

What this site does. You bring a table of measurements, it gives you numbers back. This page takes a noisy series and gives you back a smoother one, by averaging each point with its neighbors so that random noise cancels out. It runs entirely in your browser — nothing is uploaded, nothing is stored, and there is no limit on how often you use it. If you want the reasoning rather than the answer, the smoothing article walks through the methods and the trade-off none of them can remove.

1. Paste your data into the Input grid — straight from a spreadsheet, or as CSV/TSV text — or import a CSV/TSV file. First column is x, the rest are up to three y series.
2. Set the window, in points — type it, or use the ▲▼ buttons, which step through odd numbers. A typed even number is rounded to the nearest odd one so the filter has a real centre.
3. Press smooth. Each series is smoothed by a moving average - the average of the points inside the window, centred on each point. Until then the chart shows your raw data only. A paste or an import redraws the chart with the new data at once; the smoothed result changes only when you press smooth again.
4. Read the result. The Output grid carries the same x column as the Input, unchanged — there is no separate output range here, one row in gives one row out. The chart overlays raw and smoothed on the same axes so you can see exactly what the filter removed. Export saves the Output grid as a CSV/TSV file.

Near the first and last few points there are not enough neighbors for a full window. Rather than invent data that was never measured, the window shrinks to whatever real points exist — so the average near an edge uses fewer points than the one in the middle, and can differ from what a full window would have given.

The Input grid holds four columns: x plus three y series. Paste more and the extra columns are dropped with a warning. Fewer is fine — the unused columns are simply left blank.